I'm happy to see so much support for the Valcarlos route.
Due to snow, it was the route I was suddenly forced to take on my first Camino. It was little written about at that time except as a poor substitute for the Napoleón and I was disappointed.
However, it was easy for a beginner like me to follow and the services along the way were good. I followed a short alternative path at one point, feeling brave, and enjoyed it immensely. I enjoyed the valleys and the forests. I was prepared for mud and rain, so the weather presented no problem for me. It was uncrowded and peaceful in many places. It was a gradual uphill all the way until the little Chapel at the almost-end but, not knowing any better, I made the trip from SJPdP to Roncesvalles in one day with daylight to spare (I was not in great shape).
I have since walked the Napoleon and even stayed in Orrison, yet the Valcarlos is, dare I say, my route of choice. I think you are going to like it.